The present invention relates to a plasma processing apparatus for deploying a substrate-like sample such as a semiconductor wafer inside a processing chamber within a vacuum vessel and processing it using plasma formed inside the processing chamber in the fabrication of a semiconductor integrated circuit or the like, in which judgment of the end point of the processing or detection of the state inside the processing chamber during the processing or the characteristics of the processing is performed using a result obtained by detecting the light-emission from the plasma during the processing.
In the fabrication of a semiconductor wafer, dry etching is widely used for the removal or pattern formation of the layers of various materials formed on the surface of the wafer, particularly the layer of dielectric material. In this dry etching, the etching machining of the film to be processed is performed by converting an etching gas introduced into a vacuum processing chamber to plasma to generate ions and/or radicals and causing these ions and/or radicals to react with the film to be processed on the wafer.
During the dry etching processing of the semiconductor wafer, the light-emission intensity of a specific wavelength in the plasma light changes in accompaniment with progress of etching of the film to be processed. Accordingly, as one of the methods for detecting the etching end point of the semiconductor wafer, there has been a method for a long time in which the change in the light-emission intensity of a specific wavelength from the plasma is detected during the dry etching processing and the etching end point is detected, at which the film to be processed is completely removed by etching, based on this detection result.
In the dry etching processing of a wafer of a low opening ratio, on which the exposed area of the material to be etched is small, the change in the light-emission intensity at the etching end point becomes faint. Also, the light-emission intensity of a wavelength of a reaction product produced as the material to be etched is etched decreases at the etching end point.
On the other hand, the light-emission intensity of a wavelength of the etching gas (etchant) increases. In JP-A-2011-009546 or the like, there has been known the method in which faint change in the intensity at the etching end point is increased by doing division between the light-emission intensity of a wavelength of the reaction product and the light-emission intensity of a wavelength of the etchant.
In this prior art, the technology in which, in the etching processing of the low opening ratio wafer or the like in which the change in the light-emission intensity at the etching end point is faint, the faint change in the intensity is amplified by doing division between the signal whose light-emission intensity increases at the etching end point and the signal whose light-emission intensity decreases thereat is disclosed.